1. Field of the Invention
The present invention is directed to apparatus useful in the manufacture and repair of tubular products and, more specifically, to apparatus for dynamically balancing articles of substantial axial length such as automotive drive shafts.
Automotive drive shafts sometimes referred to as drive lines are comprised of a tubular member having an element such as a yoke of a universal joint, a bearing stub or one component of a slip joint fitted and welded at each end thereof.
In automotive applications, drive shafts are utilized, either singularly or in combination, as a torque transmitting component(s) of the power train and are most commonly located under the vehicle between the transmission or other gear box and the differential of a drive axle. The ends of the drive shaft are usually connected to other components of the power train by a yoke which is fitted to one end of the drive shaft and connected by means of a universal joint cross shaped journal to another yoke receiving or delivering torque from or to an adjacent component of the power train.
Torque transmitting drive shafts of this type, especially when employed on commercial vehicles and heavy duty trucks, are subject to sudden changes in torque and exposed to road hazards which, during the life of the vehicle, may cause wear or damage to the drive shaft. In the event of such wear or damage, the drive shaft may be removed and replaced in its entirely which is rather expensive. Depending upon the nature of the wear and/or damage incurred, the drive shafts may also be disassembled and repaired which is less expensive than replacing the unit, however, this option depends upon the availability of equipment necessary to disassemble and reassemble the drive shaft assembly and to balance the reassembled drive shaft and thereby avoid undesirable vibration and wear.
2. Description of the Prior Art
Various types of balancing machinery and equipment have been employed to balance drive shafts in the past. Most of these are relatively long machines having spaced spindles adapted to engage and rapidly rotate the opposite ends of a drive shaft and sensors or other devices for detecting and indicating vibration(s) induced by the rapidly rotating driveshaft. Some machines have utilized heavy cast and/or fabricated frames supporting the spindles while others have utilized cast concrete bases. However, those dynamic balancing machines which have previously utilized cast concrete bases have also used soft or resilient mounting devices for the spindles and detect imbalance at only one end of the drive.
The present invention provides a dynamic balancing machine in which the spindles are rigidly mounted to the base and enable the machine to effect a truer indication of imbalance since there are no resilient spindle mounting devices to dampen vibrations at the ends of the drive shaft. The machine also provides for simultaneous sensing and indication of vibration at each end of the drive shaft and facilitate rapid changes in the axially movable spindle as well as the attachment of the drive shaft to the spindle chuck.